This class is loaded by WebappClassLoaderBase to enable it to deregister JDBC drivers forgotten by the web application. There are some classloading hacks involved - see WebappClassLoaderBase#clearReferences() for details - but the short version is do not just create a new instance of this class with the new keyword. Since this class is loaded by WebappClassLoaderBase, it cannot refer to any internal Tomcat classes as that will cause the security manager to complain.